While my potatoes are boiling, I like to cook some diced onion until they are really brown, plus a little garlic. I don't peel my taters, just boil them, mash them up with the onions and garlic, some black pepper, and some half and half. Oh yeah, butter too, and if it's a holiday I'll put some bacon in it too. I rarely make them for just me and possibluy L, so when I do I want them to be really, really good. I like mine sort-of lumpy, and not runny at all. They should be thick enough to stand in a pile, but barely. I don't like runny mashed taters. That would be tater soup.
MRD, you are right, whatever you are using to cream the potatoes has to be hot, or you've wasted your effort.